Natural selection of glycoprotein B (gB) mutations that rescue the small plaque phenotype of a fusion-impaired herpes simplex virus (HSV) mutant

Abstract

WORD COUNT: 250 words 15 TOTAL WORD COUNT: ~4900 words 16 KEY WORDS: herpes simplex virus type 1, glycoprotein B, gB, revertant, mutation, 17 entry, fusion 18 19 2 ABSTRACT 20Glycoprotein B (gB) is a conserved viral fusion protein that is required for herpesvirus 21 entry. To mediate fusion with the cellular membrane, gB refolds from a prefusion to a 22 IMPORTANCE 41Glycoprotein B (gB) is an essential viral protein that is conserved in all herpesviruses 42 and is required for virus entry. gB is thought to undergo a conformational change that 43 provides the energy to fuse the viral and cellular membranes, however the details of 44 this conformational change and the structure of the prefusion and intermediate 45 conformations of gB are not known. Previously, we demonstrated that mutations in 46 the gB "arm" region inhibit fusion and impart a small plaque phenotype. Using serial 47 passage of a virus carrying these mutations, we identified revertants with restored 48 plaque size. The revertant viruses acquired novel mutations in gB that restored fusion 49 function and mapped to two sites in the gB ectodomain. This work supports our 50 hypothesis that an interaction between the gB arm and the core of gB is critical for gB 51refolding and provides details about the function of gB in herpesvirus mediated fusion 52 and subsequent virus entry. 53 54